Apparatus for and method of die casting under vacuum



Sept. 22, 1959 D. M. MORGENSTERN 2, 0

APPARATUS FOR AND METHOD OF DIE CASTING UNDER VACUUM Filed May :51, 19575 Sheets-Sheet 1 IN VEN TOR. 04 W0 M MMENsrER/V Q Q Y Sept. 22, 1959 D.M. MORGENSTERN 2,904,861

} APPARATUS FOR AND METHOD DIE CASTING UNDER VACUUM Filed May 31. 1957 5Sheets Sheet 2 T aw" IN VEN TOR.

v Luv/0 M Mammal-5R1 ArraR/VEY Sept.- 22, 1959 D. M. MORGENSTERN2,904,861v

APPARATUS FOR AND METHOD OF DIE CASTING UNDER VACUUM Filed May 31, 19575 Sheets-Sheet 3 INVIEN T012. .04 W0 Mmas/vsm/v Arrae/vsy p 1959 D. M.MORGENSTERN 2,904,861'

I APPARATUS FOR AND METHOD OF DIE CA STING UNDER VACUUM Filed May 31,1957 5 Sheets-Sheet 4 INV EN TOR. 0Av/0 M Maeaewszmn Arrwzwey Sept. 22,1959 D. M. MORGENSTERN APPARATUS FOR AND METHOD OF DIE CASTINGUNDERVACUUM Filed May 51, 1957 5 Sheets-Sheet 5 INVENTOR. 0 4w0 M/VoeaswszzmAfTOP/V y atent Qfirce zfifi ifibl Patented Sept. 22, 1959 APPARATUS FORAND METHGD OF DE CASTlNG UNDER VACUUM David M. Morgenstern, Euclid,Ulric, assignor, by direct and mesne assignments, to Package MachineryCon parry, East Longrneadow, Mass, a corporation of MassachusettsApplication May 31, 1957, Serial No. 662,838

19 Claims. (Cl. 22-73) This invention, like those that constitute thesubject matter of copending applications Serial No. 403,565, filedjointly by Alfred P. Federman and myself on January 12, 1954, now PatentNo. 2,799,066, issued July 16, 1957, and Serial No. 543,832, filed by mealone on October 31, 1955, now Patent No. 2,864,140, issued December 15,1958, relates to the art of die casting under vacuum; and it resides infurther improvements in both method and apparatus.

As regards the apparatus, it is my desire, as in the former cases, toadapt my improvements, insofar as it is practicable, to incorporation indie casting machines of prevailing type, although it is to be understoodthat the invention, in many of its aspects, is not limited in itsembodiment to conventional die casting equipment.

Like the more recent of the predecessor inventions, the present onefollows the so-called cold chamber procedure in the feeding of themolten material to the die cavity, minus, however, the earlier practiceof pouring the molten material into the charging chamber by means of aladle. In the present case, as in the prior one just mentioned, thecharging chamber communicates with a crucible that is situated at alower elevation than said chamber through a conduit or passage desirablyincluding a metering orifice. Where the passage opens into the chargingchamber it forms the inlet port of said chamber, and a ram operates inthe charging chamber to force molten material therefrom into the diecavity, the ram serving to close the inlet port at the very beginning ofits working stroke, thereafter, according to my present preference,opening said port to the atmosphere. As will presently appear, one phaseof the instant invention is tied in with the feeding of the moltenmaterial from the crucible to the charging chamber by reason of apressure differential between the two locales.

A device common to the present and predecessor inventions is a hood orenclosure that surrounds the dies and is so constructed as to facilitateits being opened and closed. As known to those familiar with die castingmachines of the usual sort, the dies are relatively movable toward andfrom each other, and a :die cavity is defined by and between them whenthey are in engagement. The hood is adapted to be closed and renderedsubstantially airtight, and then evacuated by subjecting its interior tosuction that is sufliciently powerful and enduring to immediately createand maintain in the hood and in all spaces communicating therewith avacuum of relatively high degree, the foregoing taking place while thedies are relatively moved toward each other and finally into engagementso as to close the die cavity and entrap therein a part of the rarifiedatmosphere prevailing in the hood. Another phase of the presentinvention pertains to unique features of the hood or enclosure.

A fundamental purpose of my present invention is to provide improved diecasting means and method that will speed up production and/or producesuperior castings as compared with the production rate and quality ofproduct of the predecessor inventions.

l wo other highly important and related objects of the present inventionare, first, to utilize atmospheric pressure for feeding the moltenmaterial from the crucible to the charging chamber, and, secondly, totake advantage of the draft incident to the evacuation of the hood orenclosure while the charging chamber is in communication therewith forcarrying oif gases liberated from the molten material while it reposesin the charging chamber and is exposed to the rarified atmosphere. Theattainment of the first of these objects contributes to speedier production, and the attainment of the second improves the quality of thecasting by further reducing porosity beyond that accomplished by thepredecessor inventions Where evacuation of the die cavity alone wasdepended upon for such purposes. It will become more apparent as thisdisclosure unfolds that die castings of denser molecular structure,smoother surface, and greater strength and malleability; and diecastings susceptible to thinner wall formations, result from my presentimprovements.

It may be pointed out as a further advantage of evacuating the chargingchamber and die cavity, that less oppo sition is offered the ram inimpelling the material into the die cavity and, therefore, the action ofthe ram is accelerated.

Another object of my invention is to provide a twosection vacuum hoodfor die casting machines wherein at least one section is adjustableand/or a part thereof removable to afford easier access to the encloseddie and thus facilitate the changing of dies, and better adapt the hoodto dies of different depths.

More limitedly, an object of the invention is to provide a vacuum hoodfor die casting machines that is composed of two sections forattachment, respectively, to the relatively movable platens, and whereinthe section associated with one platen is composed of an inner memberthat attaches to said platen, and an outer member that surrounds and isslidable upon a continuous peripheral bearing and sealing part of theinner member for movement with respect to the latter in an axialdirection.

A further object is to provide simple means, convenient of manipulation,for accomplishing and retaining the desired adjustment of the outermember of the hood section relative to the inner member.

A still further object is to construct the outer member of said hoodsection of upper and lower parts that are detachably connected togetheralong the opposite sides of the section so that the upper part may bedisconnected from the lower part and retracted as far as necessary orremoved to permit unobstructed access to the enclosed die as well as tosuch elements as may be associated therewith, i.e., ejecting mechanism,movable cores, and conduits and connections of a coolant system, allrelatively common in die casting machines.

The foregoing objects and advantages, with others that will appear asthis description proceeds, are attained in the embodiment of theinvention illustrated in the accompanying drawings, and by means ofwhich my improved method may be practiced.

In the drawings:

Fig. 1 represents, in side elevation and of simplified construction, aconventional die casting machine equipped with my improvements thatrender it capable of producing die castings under vacuum, the presentview showing the working parts in the positions they occupy betweencycles, and being largely schematic;

Fig. 2 is an enlarged vertical sectional view of the hood and adjacentparts of the machine, showing the hood and associated working parts asthey appear soon after the start of a cycle, with the hood closed andthe dies apart but with the dam extended a short distance into thecharging chamber and with a charge of molten material reposing in saidchamber;

Fig. 3 is a fragmentary transverse section on the line 33 of Pig. 2;

Fig. 4 is a view, similar to Fig. 2, showing the extensible hood sectioncontracted and the dies engaged with each other and the ram advanced tothe position it occupies when the charge of molten material has beeninjected into the die cavity;

Fig. 5 is an exploded perspective view of the adjustable hood section;

Fig. 6 is a sectional view of a valve means by which the evacuation ofthe hood is effected at one stage of a cycle of operation, and by whichadmission of atmospheric air to the hood is accomplished at anotherstage of the cycle, and

Fig. 7 is an enlarged detail view, partly in section, of the master andpilot valves, and the electrical actuator of the latter, that controlthe operation of the hydraulic power unit that operates the movableplaten, this being representative of similar control means operativelyassociated with the power unit that reciprocates the ram, the,illustration being somewhat schematic.

I have shown my improvements incorporated in a die casting machine of awell known type, simplified for the purpose of the present disclosure bythe omission of some of the usual structural features of the machine,and by a schematic illustration of others.

Throughout the several views of the drawings, like parts are designatedby like reference characters, and referring to Fig. 1, an elongated flatbed 1 supports intermediate its ends the machine base 2. Secured to andrising from the front end of the base 2 is the stationary platen 3, anda tie plate 4 rises from the opposite end of the base and is suitablyfastened thereto. Four relatively heavy tie bars 5, familiar in thistype of machine, are supported by and between the stationary platen 3and the tie plate 4. Movable along these tie bars and reciprocablysupported by the base 2 is the movable platen 6. Toggle joints 7 havetheir opposite ends connected through suitable brackets to the movableplaten 6 and the tie plate 4, and they are operated in the usual manner,by a power unit 12. Said power unit, in the present instance, consistsof a cylinder 14, carried by the tie plate 4, and a piston that operatesin said cylinder and has connection, through its rod 16 and a head 17and links it}, with the toggle joints 7.

Fastened, as in the usual manner, to the stationary platen 3 is a die20, and a mating die 22 is attached to the movable platen through aplate 23 and a plurality of posts 24 (Fig. 2), thereby to provide aspace between the die 22 and the plate 23 for the accommodation of partsof ejecting mechanism. This mechanism includes a head 25 and ejectorpins 26 that are reciprocable in bores in the die 22. A plunger 27 hasits forward end secured to the ejector head 25 and operates withinaligned bores of the plate 23 and the platen 6, the joint between theplunger and said platen being shown as sealed by an 0 ring 28. When themovable platen 6 is retracted and closely approaches the limit of itsrearward movement, the plunger 27 engages a stop 30 that is supported,through brackets, from the upper tie bars 5, one of which brackets isshown in Fig. l, where it is designated 31. This results in stoppage ofthe ejector head 25 while the platen continues to move the remainingshort distance and, through the ejector pins 26, dislodge the castingfrom the movable'die.

Operatively associated with the power unit 12 are a master die-closingvalve and a master die-opening valve 36; and the operation of thesemaster valves is effected through the respective pilot valves 35 and 36The general character and mode of operation of these valves will beapparent from Fig. 7, and valves substantially identical with these areshown and described in the above identified applications.

Mention may here be made of a switch actuator, designated generally bythe reference numeral 40, that is shown (Fig. 1) as directly connectedto the movable platen 6 so as to move in unison therewith. The actuatorincludes a rod 41 that carries, in properly spaced relation to oneanother, switch engaging fingers 43 and 44, and a switch operating cam45. In the path of movement of the fingers and cam are a ram-returnswitch as that is biased to open position, but which is held closed bythe finger 43 between cycles; a die-open limit switch 47, which isbiased to closed position and is held open by the finger 43 betweencycles, said switches including an intermediate oscillating blade commonto both and which is the part engaged by said finger; a so-calledevacuating switch 48 that is biased to open position; a die-dwell switch49 that is biased to closed position, and a die-close limit switch 50,that is biased to open position.

A die cavity 52 is defined by and between the dies 20 and 22. 53 is ahousing or shell that encloses a charging chamber 55 that is desirablycylindrical. Said chamber opens through the face of the die 20, and, inthe present construction, the forward end of the housing or shell 53projects through and is sealed in aligned openings of the stationaryplaten 3 and the die 20.

The housing or shell 53 extends rearwardly some distance beyond thefront face of the stationary platen 3 and has secured to it, by studs 57and nuts 58, means for delivering a charge of molten material to thecharging chamber comprising a supply pipe or conduit 69. Shown (Fig. 2)interposed between the supply pipe or conduit and the housing or shell53 are a thimble 61 and an insert 62 having a metering orifice 63. Thisinsert is interchangeable with others having metering orifices ofdifferent capacities, selected according to the quantity of moltenmaterial that is to be delivered to the charging chamber, as willhereinafter more fully appear. The thimble 61 is shown as reduced at itsupper end to fit within an opening in the wall of the housing or shell53, the thimble having a bore that, in the present instance, constitutesthe inlet port of the charging chamber. The opposed faces of thethirnble 61 and conduit are shown as recessed to receive the ends of theinsert 62. The supply pipe or conduit 60 may be made of cast steel,desirably lined with a durable material that is capable of withstandingvery high temperatures without deterioration, such as that commonlyknown as Spanish whiting; or the pipe or conduit may be made, in wholeor in part, of some material having the above mentioned properties, suchas carbon, especially the end portion that dips into the moltenmaterial. The pipe or conduit is shown as extending downwardly into acrucible 65 to near the bottom of the latter, and said crucible issuitably supported within a furnace casing 6, shown as having gasburners 67 located therein below the bottom of the crucible. Thecrucible 65 is open at its upper end to the atmosphere.

A ram 70 (Fig. 2) operates within the charging chamber 55 and hasconnection, through a rod 71, with a piston '72 (Fig. 1) that isreciprocable in a cylinder 73, supported by an end plate 74 of themachine, said piston and cylinder constituting a power unit designatedgenerally by the reference numeral '75 by which the ram '70 is advancedand retracted. It may be explained that when the piston 72 is at theright hand end of the cylinder 73, as the parts are viewed in thedrawings, the ram 7%) uncovers the inlet port of the charging chamberconstituted of the bore of the thir'nble 61, as shown in Fig. 2, and dueto the length of travel of said piston, the ram 76 is capable of beingadvanced to the extreme discharge end of the charging chamber. Aswil'l'more fully appear hereinafter, the operation of the power unit 75'is under the control of'master valves 76 'and77, and the operation ofthese master valves is eflected through the respective pilot valves 76and 77 An important element of the invention is a dam 80 that is carriedby the movable die 22 and projects from the face thereof in axialalignment with the charging chamber 55. The dam is fixed with respect tothe die 22 and enters the discharge end of the charging chamber whilethe die cavity is open and well in advance of the final engagement ofthe dies and the consequential closing of the die cavity, as will morefully appear as the description proceeds. The dam is shown as having anenlarged base 81 that is secured within a recess of corresponding sizeand shape in the face of the die 22, and the length of the dam in anycase is proportional to the depth of the die cavity. The chargingchamber 55, adjacent the top thereof, communicates with the die cavity52 through a runner 82, shown as a channel extending along the top ofthe dam and across the base thereof and across the adjacent portion ofthe face of the die 22.

A two-section vacuum hood or enclosure designated, generally, by thereference numeral 85 (Fig. 1), surrounds the dies 20 and 22. Therespective sections 86 and 87 of the hood are secured to the stationaryplaten 3 and the movable platen 6. The hood section 86 is made up oftelescoping parts, one part including a peripheral Wall 38 (Fig. 2) anda flange 89 that extends outwardly at right angles from the front edgeof said peripheral wall. The other part of the hood section 86 includesa peripheral wall 99 that is surrounded and partly overlapped by thewall 88, and extending inwardly from the rear end of the wall 99 atright angles thereto is a marginal rear wall 91. The hood section 86 isproperly positioned with respect to the stationary platen 3, and issecured to said platen along the top and sides thereof, by angles 93that are shown as fastened by bolts 94- to said marginal wall, and byscrews 95 to said platen. A flexible wall section or bellows 96 has itsfront and rear edges respectively secured by suitable means and inleakproof manher to the telescoping peripheral walls 8% and 90 of thehood section 86, a gasket 97 being shown as carried by the wall 88 forsliding engagement with the Wall 90.

It is apparent from the construction described that the hood section 86is extensible. Its axial elongation or expansion is limited by bolts 1%that are fixed to brackets 101 that extend upwardly and laterally fromthe rear of the hood section Sn and the said belts are slidable throughapertures in brackets 192 that are attached to and extend upwardly andlaterally from the flange 89. Springs 1% surround the bolts 1% and tendto retain the hood section 86 extended.

The hood section 37 is composed of an inner member 167 and an outermember 108, the latter consisting of a longitudinally extending wallthat is slidable in an axial direction on a peripheral bearing part 169of the inner member, said part being composed of sealing material, suchas rubber of a suitable nature, so as to seal the joint between themembers. A flange 11% surrounds and extends outwardly from the wall ofthe outer member in spaced relation to the front edge of said wall, andan angle 111 is applied to the front face of said flange adjacent theouter edge thereof which, with the opposed edge portion of the aforesaidwall, provides a channel within which is secured a sealing strip 112 ofrubber or the like, arranged for contact with the flange 89 of the hoodsection 86. A flange 113 is shown as extending outwardly from.- the topand sides of the rear end of the longitudinal wall of the member 108.

The inner member 1117 of the hood section 87 is a frame-like unit, asbest appears from Fig. 5. Said member includes a transversely disposedmarginal Wall 115 that is secured to the inner face of the movableplaten 6 by screws engaged through apertures in the wall 115 andthreaded into the platen. The member 107 has a forward offset 113 thatextends across the bottom and a short distance up the sides of themember, and the aforesaid peripheral bearing part 109 follows the edgeof the marginal wall above the offset 118 and then continues across thetop and front edges of said oflset. This formation of the inner member107 is made necessary by the fact that the bottom portion of thelongitudinal wall of the outer member 108, where it is designated 119 inFigs. 2 and 5, is shortened to accommodate the lower end of the movableplaten 6.

The outer member 108 is divided into top and bottom parts in thehorizontal plane of the upper edges of the forward offset 118 of theinner member 107. The adjacent ends of the divided side walls of theouter member are provided with flanges 120 and 121 between which arecompressed gaskets 122 when the flanges are drawn together by bolts 123that are engaged through aligned holes in said flanges and gaskets. Thisconstruction enables the top part of the hood section 87 to bedisconnected from the bottom part and fully retracted or, as analternative, lifted from the platen 6, in either event to facilitate thechanging or mounting of the die that is carried by said platen.

The axial adjustment of the hood section 87 better adapts it to dies ofdifferent depths and dams 80 of proportional lengths. For the purpose ofsuch adjustment, and to hold the outer member 193 in the desiredadjusted. position with respect to the inner member 107, threaded studs125 are secured to and extend rearwardly from the marginal wall 115 ofthe inner member in properly spaced relation across the top and down thesides thereof, and notched lugs 12s are secured to the flange 113 of theouter member 1418 and straddle the studs. Nuts 127 and 128 are threadedupon each of the studs 125, and the corresponding lug 126 may be clampedbetween said nuts in any position to which it is adjusted along the studand, in fact, by running one of the nuts along the stud to the desiredposition, the other nut may be employed for urging the lug intoengagement with the former nut in the adjustment of the hood section. Itwill be observed that the notches of the lugs 126 open downwardly sothat, if desired, the nuts 127 and 128 may be relaxed and the top partof the hood section 87 (lifted from the machine, as hereinbeforementioned.

The means for evacuating the hood '85 is shown in Pig. 1. It comprises avacuum pump 131), driven by an electric motor 131, through a flexibledriving element or belt 132, and a vacuum tank 133. The vacuum tank 133has connection through a conduit 135 of relatively large diameter with abox-like fitting 136. Said fitting is joined to the rear wall 91 of thehood section 86 and communicates with the interior of the hood through aslot 137 (Fig. 3) in said wall.

In the conduit 135 is valve means designated generally by the referencenumeral 140, shown in sectional detail in Fig. 6. Within a cruciformcasting 141 of said means operates a vacuum valve 142 that is movedtoward and from a seat 143 by a power unit comprising a cylinder 1%Within which a piston 145 reciprocates. The cylinder is carried by anend plate 146 that is fastened to the front horizontal branch of thecasing 141, the opposite branch having communicative connection withthat portion of the conduit 135 that leads to the vacuum tank 133. Thevacuum valve 142 is carried by an extension of the piston rod 147. Anapertured plate 148 is fastened to the top of the casing 141, andattached to and spaced above said plate, by posts 149, is a member 150that mounts a power unit consisting of a cylinder 151 and a piston 152.The inner end of the previously mentioned cylinder 144 is placed incommunication with the outer end of the cylinder 151 by a pipe 153,while a pipe 154 communicatively connects the inner end of the cylinder151 with the outer end of the cylinder 144. Cooperating with an upwardlyfacing seat 155 that surrounds the aperture of the plate 148 is arelatively large disc valve 156 that is surmounted by a casing 157 of anauxiliary valve 158, the latter valve cooperating with a seat thatsurrounds a central opening 159 in the disc valve 156. The valve 158 isconnected to the rod 160 of the piston 152, and said auxiliary valve islimited in its retraction by the top of the casing 157. The casing 157is open to the atmosphere through perforations 161.

It is apparent from the nature of the communicative connections betweenthe cylinders 144 and 151 that the respective pistons within saidcylinders will simultaneously move in reverse directions. Accordingly,when the vacuum valve 142 is urged into contact with seat 143 tointerrupt communication between the hood 85 and the tank 133, theauxiliary valve 158 will first be raised from its seat to allow air toenter through the perforations 161, thereby to relieve suction on thedisc valve 156, and further movement of the auxiliary valve wr'il engageit with the top of the casing 157 that is attached to the disc valve 156and lift the disc va'lve from the seat 155 as the piston 152 completesits upward movement.

The power units associated with the valve means 1453 are operated bypressure fluid, preferably compressed air, and the supply of pressurefluid to said units is controlled by a valve 165 (Fig. 1). This valve isshown as a spool valve of common and well known character. Stems of thespool extend from the ends of the valve casing, and a spring 166operatively connected to one stem tends to retain the spool in aposition wherein the valve directs the pressure fluid from a suitablesource (not shown) through pipes 168 and 169 to the outer end of thecylinder 14-4, thereby to move the piston 145 in a direction to engagethe vacuum valve 142 with the seat 143, the fluid from the other end ofthe cylinder escaping through pipes 170 and 171. At the same timepressure fluid flows from the outer end of the cylinder 144 through thepipe 154 to the inner end of the cylinder 151, thereby to retract thepiston in the last mentioned cylinder and lift the valves 158 and 156from their respective seats and admit atmospheric air to the hood 85. Itmay be explained that while pressure fluid is being delivered in themanner above described to the inner end of the cylinder 151, the fluidfrom the opposite end of said cylinder escapes via the pipe 153, theinner end of cylinder 144, and the aforesaid pipes 170 and 171. Aso-called vacuum solenoid 173 is arranged to move the spool of the valve165 in opposition to spring 166 and when energized, reverses theconditions above described, thereby to close air valves 156 and 158 andopen the vacuum valve 142.

I shall now describe the operation of the die casting machine and thevacuum apparatus wherewith it is equipped. In the course of thedescription I will introduce the electrical circuits, devices andinstruments that make up the control system illustrated diagrammaticallyin Fig. 1, and by which the actions of the machine and apparatus are socoordinated and governed as to render automatic a complete cycle ofoperation initiated by the closing of a starting switch.

The main circuit from which the electrical power is derived isrepresented by conductors 180 and 181, the current flowing from theformer and returning to the latter. The wires or conductors that make upthe various circuits will be referred to as lines. The oscillating bladethat constitutes a part of both the ram-return switch 46 and thedie-open limit switch 47, hereinbefore referred to, is connected to theconductor 180 by a line 182. As appears in Fig. 1, wherein the machineis shown between cycles, the ram-return switch 46 is closed, being leftin such condition at the conclusion of the previous cycle. Therefore,the current continues on from the ram-return switch 46 through a line183 to a solenoid 184 that actuates the pilot valve 7'7 which, in turn,controls the master valve 77 and causes it to deliver pressure fluid tothe power unit 75 that operate the ram 71), the ram, under prevailingconditions, being in retracted position, as shown in Fig. 2. The currentreturns from solenoid 184 through a line 185 to the side of the maincircuit represented by the conductor 181. At a junction designated 186,a line 187 leads from line 183 to the Winding of a relay CR3, theopposite end of the winding having connection, through a line 188, withthe previously mentioned return line 185. It is evident, therefore,that, between cycles, the relay CR-3 remains energized. Ob viously, whenthe machine is to be left idle for an appreciable length of time, thesupply of current to the control system may be shut off. However, aslong as the system is supplied with current, and the relay CR-3 remainsenergized, the switches incorporated therein will occupy positionsreverse to those shown in Fig. 1.

To initiate a cycle of operation, a starting switch 190', desirably ofthe push button type and biased toward open position, is momentarilyclosed. Current then flows from conductor 18%) through a line 191 thatcontains said switch to the winding of a relay CR-1 and thence, througha line 192, to line 185 and back to the return side of the main circuit.Energization of the relay CR-1 results in the closing of a switch 194that is a part of said relay, and now current flows from a junction 195of line 191, through a line 196, a normally closed switch 197 that is apart of a relay CR-4, a line 198 to the previously mentioned presentlyclosed switch 194 and then through a part of line 191, the winding ofthe relay CR-1, and

lines 192 and 185 to the return side of the main circuit. Theestablishment of this second circuit, which occurs substantiallysimultaneously with the closing of the starting switch, locks in relayCR-l, so to speak, thereby to retain switch 194 in closed conditionafter release of the starting switch 198.

At the time current is being supplied to the relay CR1, current willflow from a junction 199 of the line 191 through a line 280 to thenormally closed die-dwell switch 49 and thence, through a line 2111, towhat I shall term the dieclose solenoid 2112. From said solenoid thecurrent flows through a conductor 203 to the return side of the maincircuit. When the die-close solenoid 202 is energized, it will cause thepilot valve 35' to so condition the master valve 35 that pressure fluidwill be delivered through a conduit 205 to the outer end of the cylinder14, moving the piston 15 forwardly. Through the operative connectionsalready described between said piston and the platen 6, said platen willbe moved forwardly until the sealing strip 112 of the hood section 87engages the flange 89 of the hood section 86, thereby to close andsubstantially seal the hood 85. The relation of the dies at this stageis illustrated in Fig. 2. With the dies spaced apart as shown, theforward end of the dam 8t} occupies the discharge end of the chargingchamber 55. Said chamber now communicates, adjacent the top thereof,through the outer end portion of the runner 82, with the interior of thehood.

While the pressure fluiddesirably oil or other suitable liquid underpressureis being delivered as aforesaidthrough the conduit 285 to theouter end of the cylinder 14-, the fluid or liquid is escaping from theinner end of said cylinder through a conduit 206. The exhausted fluid orliquid is diverted by the master die-opening valve 36 through a pipe 287to a source of supply, such as a tank (not shown). its presentcondition, the pressure fluid will be conveyed through a pipe 210, froma source of supply (not shown), through the valve ports, and a conduit211, to the master valve 35 and through ports of said valve to thepreviously mentioned conduit 2415. It will be understood that the mastervalve 36 is conditioned to perform With the master valve 36 intheplaten, the finger 43 of the switch actuator will withdraw from theoscillating blade that forms a part of the switches 46 and 47, and inits released condition said blade will change its position so as to openthe ram-return switch 46 and close the die-open limit switch 47.

Upon the opening of the ram-return switch 46, flow of current throughthe previously described circuits represented by the lines 183, 185 and187 is interrupted, thereby deenergizing solenoid 184 and the relayCR-S. Energization of said solenoid 184, it will be remembered, resultedin the retraction of the ram 70', in which position it is shown in Fig.2.

The forward travel of the movable platen 6 is arrested, with the partspositioned as shown in Fig. 2, by reason of the engagement of the cam 45with the die-dwell switch 49, resulting in the opening of said switch.

Upon the opening of the die-dwell switch 49, the flow of current throughthe previously described circuit including said switch will cease,causing deenergization of the die close solenoid 202. Upon this takingplace, the pilot and master valves will resume normal condition,depriving the power unit 12 of motive fluid, and as a consequence thepiston 14 of said power unit will stop before reaching the forward endof the cylinder 15, and the die 22 will be caused to dwell, so to speak,in the position shown in Fig. 2.

Substantially simultaneously with the opening of the die-dwell switch49, the evacuating switch 48 is closed by the cam 45. Thereupon currentflows from the line 182, at the junction 214, through a line 215, switch48, and line 216 to a so-called vacuum timer T-1 and thence through aline 217 to the previously mentioned line 185 that leads to the returnside of the main circuit, represented by conductor 181. At the momentthe vacuum timer T-l was supplied with current, the vacuum solenoid 173Was energized through a circuit represented by a line 220 which is, ineffect, a continuation of line 216 beyond the timer T1, and this line220 is connected, through a switch 221 of the relay CR2, with a line 222that carries the current to the vacuum solenoid 173, the current beingconducted from the latter to the return side of the main circuit throughlines 223 and 185.

When the solenoid 173 is energized, it conditions the valve 165 todeliver pressure fluid, desirably compressed air, from a suitable source(not shown) through pipes 168 and 170 to the inner end of the cylinder144 thereby to retract the piston 145 and withdraw the vacuum valve 142from the seat 143, it being understood that the fluid ahead of thepiston will escape through the pipe 169, a port of the valve 165, andthe exhaust pipe 174. Simultaneously with the opening of the vacuumvalve 142, the air admitting Valves 158 and 156 will be seated throughreverse action of the piston 152 in the cylinder 151, the pressure fluidcontinuing on from the cylinder 144 through the pipe 153 to the outerend of the cylinder 151, while the fluid below the piston 152 escapesthrough the pipe 154, the outer end of the cylinder 142 and thence, asabove described, to the atmosphere through the exhaust pipe 174.

Thus, during the interim between energization and subsequent operationof the vacuum timer T-l, and while the dies 20 and 22 are in spacedrelation, as illustrated in Fig. 2, the hood 85 is evacuated and,because of the relative capacity of the tank 133 and the largeness ofthe conduit 135, a vacuum of relatively high degree, for example, 12 to19 inches Hg, is quickly created in the hood, and this condition iscommunicated through the runner 82 to the charging chamber 55. Under theatmospheric pressure imposed upon the top of the body of molten materialin the crucible 65, a part of said material will rise through the supplypipe or conduit 60, and through the metering orifice 63, to the chargingchamber 55, wherein the material will gradually accumulate, beingretained in the chamber by the dam 80. While 10 the molten materialreposes in the charging chamber, where it is exposed to the rarifiedatmosphere, occluded gases will be liberated and carried off through theadjacent end of the runner 82 and the interior of the hood. Theseconditions will prevail until the vacuum timer T-l functions.

In accord with the conventional performance of such instruments, after aperiod of time for which it is set, the timer T-1 operates to close aswitch 225 that is incorporated in the timer, thereby to establish acircuit which is a substitute for the former circuit that was madethrough the presently opened die-dwell switch 49 and that includes thedie-closing solenoid 202. The present circuit is represented by a line226 that connects, through a junction 227, with a part of the line 191that presently receives current from the line 198 through the switch194. The line 226 leads to the switch 225, and from said switch thereextends a line 229 that supplies current to the die-close solenoid 202,the current continuing to the return side of the main circuit throughthe line 203.

Under the circumstances just described, the pilot valve 35 will again beconditioned to operate the master valve 35 and deliver pressure fluidthrough the conduit 205 to the outer end of the cylinder 14. This willresult in moving the piston 15 forwardly for the remainder of its strokeand, through its connections with the toggle joints 7, straighten outsaid joints to move the platen 6 so as to bring the die 22 intoengagement with the die 20 and close the die cavity, as shown in Fig. 4.

Immediately upon the closing of the dies, the finger 44 of the switchactuator 40 engages and closes the die-close limit switch 50, thereby toestablish a circuit that receives current through the presently closeddie-open limit switch 47 and is represented by a line 230 that leadsfrom said switch 47 to the switch 50, and a line 231 that leads from theswitch 50 to a solenoid 233. Current thus delivered to the solenoidreturns by way of lines 234 and 185 to the side of the main circuitrepresented by the conductor 181. Upon energization of the solenoid 233,the pilot valve 76 functions to receive pressure fluid from a source(not shown) through a conduit 235, ports of the pilot valve, and deliverit through a conduit 236 to the master valve 76, conditioning saidmaster valve to deliver pressure fluid, from a source not shown, throughconduits 237 and 238 to the outer end of the cylinder 75, thereby tomove the piston 72 forwardly and, through the rod 71, advance the ram inthe charging chamber 55 and impel the molten material into the diecavity 52. This advancement of the ram continues until the die cavityand the runner 82 are filled and a slug of the material is left in thecharging chamber between the ram and the darn 80, the advance movementof the ram being stopped by the unyielding slug of material. The partsare illustrated in this condition in Fig. 4.

Concurrently with the energization of the solenoid 233, which resultedin the advancement of the ram 70, relay CR-2 is energized by currentconducted to the winding thereof through a line 235 that leads, at ajunction 236, from the aforesaid line 231, current being conducted fromsaid winding through a line 237, and the former line 1 85 to the returnside of the main circuit. A switch 240, which is a part of relay CR-Z,closes when the relay is energized and locks in relay CR-Z, so to speak,through a circuit which becomes a substitute for the former one by whichsaid relay was initially supplied with current, after said formercircuit is opened. This substitute circuit is represented by a line 241,that leads from a junction 242 with line 230 adjacent die-open limitswitch 47 to a switch 243 of relay CR-3; a line 245 that leads to thepreviously mentioned switch 240 of relay CR-2, and a line 246 that joinsan adjacent part of line 235 leading to the winding of the solenoidCIR-2, the current being carried thence through the former circuitcomprised of lines 237 and to the return side of the main circuit,

It may be mentioned at this point that the current from line 246 dividesin advance of relay CR2, a part of it being presently diverted tosolenoid 233 through the inte'rvening parts of lines 235 and 231. Also,upon the energization of the relay CR2, its switch 221 opens, whichinterrupts the flow of current through the previously described circuitcontaining said switch and the vacuum solenoid 173. Therefore, upon theopening of said switch 221 and the resultant deencrgization of solenoid173, the valve 165 is returned to normal position by the spring 166which conditions said valve to deliver pressure fluid through the pipe169 to the outer end of the cylinder 144 and the inner end of cylinder151. As a consequence, the vacuum valve 142 will be closed and the airadmitting valves 156 and 158 opened in the manner previously described.At the present time, therefore, atmospheric pressure prevails in thehood so that section 87 thereof may be moved away from section 86without danger of damage to the sealing strips of the inner and outermembers of the hood section 87, which might reasonably be expected ifthe hood were opened while under an appreciable degree of vacuum.

Further, upon energization of relay CR-Z, a switch 243 thereof isopened, interrupting the flow of current through a circuit that may bedescribed as comprising a line 250, which receives current from the line196 at junction 251 and leads to a switch 252 of relay CR3; a line253that leads from said switch to the previously mentioned switch 248 ofrelay CR-2; a line 254 that leads from the latter switch and joins line1557 at junction 255; a part of said line 187; the winding of thesolenoid (IR-3, and lines 183' and 185, the latter leading to the returnside of the main circuit. Therefore, energization of relay CR-2 opensthe circuit just described which supplies, under certain circumstances,current to the relay CR3, and the latter relay, as will be remembered,is responsible for supplying current to the solenoid 184. Referringagain to the energization of relay CR-Z, when this occurs it closes afurther switch 257 incorporated in. said relay and establishes a circuitfrom line 241, through a short branch leading therefrom to one side ofsaid switch 257, the opposite side of the switch being connected,through a line 258, with a timer T-Z. The circuit including the timerT-2 is completed through a line 260 which leads to a junction 261 withline 185 which carries the current to the return side of the maincircuit.

After a time interval for which the instrument is set, timer T-2functions and closes a switch 262 thereof. The closing of this switchestablishes a circuit that receives its current from line 241, at ajunction 263, and is represented by a line 264 that leads to saidswitch'262, and a line 265, leading from said switch to a so-calleddieop'en' solenoid 266, the current returning from said solenoid througha line 267, an adjacent part of the previously mentioned line 260, andline 185 to the side of the main circuit represented by the conductor181.

Simultaneously with the closing of the above mentioned circuit whichsupplies current to the die-open solenoid 266, a further circuit isestablished through a line 270 that leads from its junction with line265 to one end of the winding of a relay CIR-4, the opposite end of thewinding being connected through a line 271 with the return line 185;Energization of this relay effects the closing of a switch 272' of saidrelay that is in a circuit represented by a line 273 that leads from ajunction 274 of line 264 to the part of the previously mentioned line270 throughwhich current is supplied to the winding of the relay (ZR-4.By virtue of this last described circuit, the relay CR-4 will remainenergized after the switch 262 of' timer T2' opens. Also, by reason ofthe energization of relay CR-4, the switch 197 thereof will be openedarid deprive relay CR1 of current, resulting in theopening' of switch194 of the latter relay.

The purpose ofthe timer T-2is to determine the length of time thedie'cavity 52"remains closed while'thecasting' 12 is being chilled.Therefore, at the conclusion of the time interval for which theinstrument is set, the timer T-2 functions to open the switch 262 anddiscontinue the supply of current to the die-open solenoid 266.Deenergization of this solenoid will permit the spring 208 to positionthe valve member of the pilot valve 36 so as to condition master valve36 to deliver pressure fluid'through the conduit 206*[0 the inner end ofthe cylinder 14 and permit return of fluid from the opposite end of thecylinder through the conduit 28 5 and ports of the master valve 35' to aconduit 275 that leads back to the source of supply. This will result inthe movement of the piston 15 to the outer end of the cylinder 14. Byreason of the operative connections between said piston and the movableplaten 6 above described, said platen will be retracted to the positionshown in Fig. 1. Obviously, this will cause the hood to open since thesection 87 thereof is attached to and moves with the platen 6.Similarly, the die 22 will move away from die 20, retracting the darn 8tand as the dam withdraws from the discharge end of the charging chamber55, the ram 70 will advance to the discharge end of said chamber,pushing the slug of material ahead of it, said slug being connected tothe casting by the strip of material that solidified in the runner 82.As the platen 6 nears the end of its return travel, the plunger 27 ofthe ejecting mechanism will strike the stop 30, arrest movement of thehead 25 and ejector pins 26, thereby to strip the casting from the faceof die 22 in the final return movement of the platen 6.

During the return trip or" the platen 6, effected in the manner abovedescribed, the cam 45 of the switch actuator 40 that is carried by saidplaten will withdraw from the switches 48 and 49, resulting in theopening of the former and the closing of the latter. Opening of switch48' causes deenergization of the vacuum timer T-l, and the closing ofswitch 49 reestablishes in part the previously described circuit thatincludes the die close solenoid 202.

As the platen 6 arrives at the end of its return trip, the finger 43 ofthe switch actuator 40 closes the ramreturn switch 46, and opens thedie-open limit switch 47. The closing of the switch 46 reestablishes theabove described circuit that includes the solenoid 1S4, energizing saidsolenoid so as to effect, through the valves associated therewith, theretracting of the piston 72, and of the ram 70 connected thereto. T heclosing of the switch 46 also reestablishes the previously describedcircuit that includes the winding of relay CR-3. Accordingly, this relayand the solenoid 184 are left energized at the conclusion of a cycle, asexplained at the beginning of this description of the operation of theapparatus. When the die-open limit switch 47 opens, the supply ofcurrent is cut off from the solenoid 233 and from the relay CR2,deenergizing both. As a result of the deenergization of the relay CR-Z,the circuits controlled by the switches 240 and 257 will be opened, andthe circuits controlled by switches 248 and 221 will be closed, inpreparation for the succeeding cycle.

Now that I have described in detail a complete cycle of operation of thedie casting machine and vacuum app-aratus, as well as having describedthe circuits and parts of the control system and the manner in whichthey perform, I may summarize by reciting, briefly, the sequence ofsteps that constitute a cycle of operation. The cycle is started bypushing the button 19%. Thereupon, the movable platen travels forwarduntil the hood section 87 engages the section 86 and closes andsubstantially sealsble through the supplypip'eor conduit 60"into thecharging" Chamber, where it is retained by the dam 89. 'During itsoccupation of the charging chamber and its exposure to the rarifiedatmosphere therein, the molten material is degassed. The platen 6 nowresumes its travel and continues to the limit of its forward movement,which results in engagement of the dies and the closing of the diecavity, a part of the rarified atmosphere being entrapped in the latter.The ram 70 is now advanced, forcing the molten material from thecharging chamber 55 through the runner 82 into the die cavity 52,filling the die cavity and runner and leaving a slug of the material inthe charging chamber. Communication between the vacuum hood and theevacuating means is shut off and atmospheric air is admitted to thehood. The parts remain in the present condition until the materialsolidifies and chills sufficiently to permit exposure to the atmosphere.Thereupon the movable platen is retracted, withdrawing the die 22 fromthe die 20, and as the dam 80 leaves the charging chamber it is followedby the solidified slug of material under the impel ling force of the ram70. At the same time the hood section 87 is moved away from the section86, thus opening the hood. As the platen 6 closely approaches the limitof its return movement, the ejecting mechanism is caused to function byengagement of its plunger 27 with the stop 30, stripping the castingfrom the face of the die 22 by means of the ejector pins 26, theoperator now removing the casting in the usual way.

My improved method, as carried out, for example, by means of the abovedescribed apparatus, and in its comprehensive form, comprises thefollowing steps, to-wit: enclosing the dies in a substantially airtightenclosure; damming the lower portion of the discharge end of thecharging chamber so as to retain molten material in the chamber withoutinterrupting communication between the chamber and the die cavity; withthe dies apart, subjecting the interior of the enclosure to a suctionsufficiently strong and enduring to create and maintain a vacuum ofrelatively high degree in the enclosure and the spaces communicatingtherewith including said charging chamber, and as a result of whichmolten material is induced to flow from the container into the chargingchamber where occluded gases are liberated and drawn oif through theenclosure; restricting, in ways hereinafter explained, the amount ofmolten material thus delivered to the charging chamber to a size chargethat will fill the die cavity and runner and, desirably, leave a slug ofthe material in the charging chamber; relatively moving the dies intoengagement with each other and thus close the die cavity and entraptherein a part of the rarified atmosphere; forcing the molten materialfrom the charging chamber into the die cavity; closing off the hood fromthe suction and admitting atmospheric air to the hood; chilling thematerial to solidify it and form a casting; opening the enclosure andmoving the dies apart for the removal of the casting, and simultaneouslytherewit pushing the solidified slug of material from the chargingchamber.

The size of the charge, or, in other words, the quantity of moltenmaterial delivered to the charging chamber during each cycle ofoperation, and which, desirably, is somewhat in excess of that requiredto fill the die cavity 52 and the runner 82, is dependent upon one ormore of the following three factors: (1) the size of the meteringorifice 63; (2) the amount of time allotted to the feeding of thematerial to the charging chamber, and (3) the degree of vacuum in thehood 85. This latter factor may be controlled, for example, by a damper280 in the form of a slide, shown as incorporated in the system betweenthe valve means 140 and the slot 137 through which the fitting 136communicates with the interior of the hood. The latter way ofdetermining the size of the charge, provided it materially lowers thedegree of vacuum, should be used only when the quality of the casting isnot of major importance. For the best results as to density andidsmoothness of the casting, a vacuum of not substantially less than 19inches Hg should be used.

Obviously, by combining two or all of the foregoing factors in properproportion, a charge of the desired size may be obtained. In practice, Ihave used an insert 62 having a metering orifice of a capacity tomeasure roughly the amount of molten material required for a charge, andthen modified the amount to obtain a charge of the desired size byaltering the time factor, the latter being accomplished by adjusting thetimer T4.

So that a more practical impression of the invention may be had, I mayexplain, by way of example, that the die casting machine disclosedherein is of the 400 ton class, or, in other words, locks the dies in,so to speak, at approximately 400 tons pressure; that the vacuum pump130 is a 10 hp. pump having a displacement of 250 cu. ft. per minute;that the tank 133 is of 100 cu. ft. capacity, and that the capacity ofthe vacuum hood is 12. cu. ft. With the machine cycling every nineseconds, in accordance with prevailing procedure, and the pump operatingat its prescribed speed, a vacuum of 22 inches Hg will build up in thetank between cycles. Upon the opening of the evacuating valve 142, avacuum of approximately 19 inches Hg will be effected in the closed hoodalmost instantly, i.e., in one-half second, the vacuum in the tankleveling olf to a like value during the evacuating phase.

It is to be understood that the invention, as to certain of its phases,is applicable to the handling of plastics. Therefore, the term moltenmaterial, as herein used, embraces plastics when the latter is in aliquid state, or when in a soft, mobile condition, regardless of howsaid condition is produced, whether by heat or otherwise, as long as thematerial is capable of flowing or of being impelled into the die cavityand thereafter solidifying.

Having thus described my invention, what I claim is:

1. In a die casting machine of the type characterized by dies that arerelatively movable toward and from each other and by and between which adie cavity is defined; a charging chamber that opens through the face ofone die, a dam projecting from the face of the other die and arranged toenter the charging chamber upon relative movement of the dies towardeach other, the dam and dies having contiguous parts that conjointlyform a runner adjacent the top of the chamber providing the onlycommunication between the chamber and the open die cavity, and the dambeing formed to fit the chamber to prevent the flow of molten materialtherefrom except through the said runner, means for delivering a chargeof molten material to the charging chamber, an enclosure that surroundsthe dies and is adapted to be opened and closed and that is closedduring relative movement of the dies toward each other, evacuating meansfor creating a vacuum of relatively high degree in the enclosure whilethe dies are apart and as a result of which occluded gases in thematerial reposing in the chamber are liberated and carried from thechamber through the enclosure under the influence of the evacuatingmeans, means for rela tively moving the dies to engage them with eachother and close the die cavity while said enclosure is in evacuatedcondition, and means for transferring the molten material from saidchamber to the die cavity through the said runner.

2. In a die casting machine of the type including dies that arerelatively movable toward and from each other and by and between which adie cavity is defined; a charging chamber that opens through the face ofone die, a dam projecting from the face of the other die and arranged toenter the charging chamber upon relative movement of the dies towardeach other, the dam and dies having contiguous parts that conjointlyform a runner that opens into the chamber adjacent the top thereof andthrough which said chamber communicates with the die cavity, the dambeing otherwise formed to fit the charging chamber to prevent the flowof molten material there- I from except through said runner, atwo-section enclosure surrounding the dies and relatively movable in themanner of the dies, one section being axially extensible andco'ntractible, means biasing said section to extended condition, thesections engaging to render the enclosure substantially airtight uponinitial relative movement of the dies toward each other, means fordelivering a charge of molten material to the charging chamber,evacuating means for creating a vacuum of relatively high degree in theenclosure while the dies are apart and as a result of which occludedgases in said material are liberated and carried off from the chargingchamber through the enclosure under the influence of the evacuatingmeans, means for relatively moving the dies to engage them with eachother and close the die cavity while said enclosure is in evacuatedcondition, and means for transferring the molten material from thecharging chamber to the die cavity when the dies are in engagement witheach other.

3. In a die casting machine of the type including dies that arerelatively movable toward and from each other and by and between which adie cavity is defined; a chamber in constant communication with the diecavity, means for delivering a charge of molten material to saidchamber, further means for retaining the charge of molten material insaid chamber while the dies are apart, a twosection enclosuresurrounding the dies and the sections whereof are relatively movable inthe manner of the dies, one section comprising an inner member that isfixed with respect to the corresponding die and has a continuousoutwardly facing peripheral bearing part, and an outer member thatsurrounds the inner member and is shiftable in an axial direction uponsaid bearing part, the latter providing a substantially leakproof jointbetween the members, means for shifting the outer member axially of theinner member, the sections meeting to render the enclosure substantiallyairtight upon incipient relative movement of the dies toward each other,evacuating means for creating a vacuum of relatively high degree in theenclosure while the dies are apart and as a result of which occludedgases in the material are liberated and carried off from the chargingchamber through the enclosure under the influence of the evacuatingmeans, means for relatively moving the dies to engage them with eachother and close the die cavity while said enclosure is in evacuatedcondition, and means for transferring the charge of molten material fromthe charging chamber to the die cavity.

4. In a die casting machine of the type including dies that arerelatively movable toward and from each other and by and between which adie cavity is defined; a charging chamber that opens through the face ofone die, a source of molten material at a lower elevation than saidchamber and wherewith the chamber communicates, said source beingsubjected to the influence of atmospheric pressure, a dam projectingfrom the face of the other die and arranged to enter the chargingchamber upon incipient relative movement of the dies toward each other,the dam and dies having contiguous parts that conjointly form a runnerthat opens into the charging chamber adjacent the top thereof andthrough which said chamber communicates with the die cavity, the dambeing otherwise formed to fit the charging chamber to prevent the flowof molten material therefrom except through said runner, a twosectionenclosure that surrounds the dies, the sections whereof are relativelymovable in the manner of the dies and which sections are engaged witheach other to render the enclosure substantially airtight before thedies are engaged with each other, evacuating means for creating a vacuumof relatively high degree in the enclosure while the dies are apart andas a reuslt of which a charge of molten material is induced to flow fromsaid source into the charging chamber where occluded gases in thematerial are liberated and carried off through the enclosure under theinfluence of the evacuating means, means for relatively moving the diesto engage them with each other and close the die cavity while saidenclosure is in evacuated condition, and means reciprocable in thecharging chamber and acting to shut off the flow of molten material tothe chamber and impel the charge of molten material from the chamber tothe die cavity.

5. In a die casting machine of the type including dies that arerelatively movable toward and from each other and by and between which adie cavity is defined; a charging chamber that opens through the face ofone die, a source of molten material at a lower elevation than saidchamber and wherewith the chamber communicates, said source beingsubjected to the influence of atmospheric pressure, an element having ametering orifice in the path of communication between the chargingchamber and said source, a dam projecting from the face of the other dieand arranged to enter the charging chamber upon incipient relativemovement of the dies toward each other, the dam and dies havingcontiguous parts that conjointly form a runner that opens into thecharging chamber adjacent the top thereof and through which said chambercommunicates with the die cavity, the dam being otherwise formed to fitthe charging chamber to prevent the flow of molten material therefromexcept through said runner, a two-section enclosure that surrounds thedies, the sections whereof are relatively movable in the manner of thedies and which sections are engaged with each other to render theenclosure substantially airtight before the dies are engaged with eachother, evacuating means for creating a vacuum of relatively high degreein the enclosure while the dies are apart and as a result of which acharge of molten material is induced to flow from said source into thecharging chamber where occluded gases in the material are liberated andcarried ofi through the enclosure under the influence of the evacuat ingmeans, means for relatively moving the dies to engage them with eachother and close the die cavity while said enclosure is in evacuatedcondition, and means recipro cable in the charging chamber and acting toshut off the flow of molten material to the chamber and impel the chargeof molten material from the chamber to the die cavity.

6. Improvements in die casting machines of the type including thefollowing: dies that are relatively movable toward and from each otherand by and between which a die cavity is defined; die operating meansfor moving the dies as aforesaid thereby to open and close the diecavity; a charging chamber that opens through the face of one die and isin communication with a source of molten material at a lower elevationthan said chamber, said source being subjected to the influence ofatmospheric pressure; a ram reciprocable in the charging chamber forforcing molten material from the charging chamber into the die cavity,and ram reciprocating means; said improvements comprising in combinationtherewith a dam projecting from the other die and arranged to enter thecharging chamber during movement of the dies toward each other, the damhaving a channel on the top side thereof that opens through its distalend and the dam being otherwise formed to fit the charging chamber toprevent the flow of molten material therefrom except through saidchannel, opposed pa: 5 of the dies conjointly forming a passage throughwhich said channel communicates with the die cavity, an enclosureencompassing the dies that is adapted to be opened and closed and thatis closed during relative movement of the dies toward each other, andevacuating means in communication with the enclosure for creatingtherein a vacuum of relatively high degree while the dies are apart andas a result of which a charge of molten material is induced to flow fromsaid source into the charging chamber, the die operating meansfunctioning in the course of a cycle of operation of the machine toengage the dies and close the die cavity, and the ram reciprocatingmeans acting to advance the ram and force a sufficient quantity of saidmaterial into the die cavity to fill the latter.

7. Improvements in die casting machines of the type characterized by thefollowing: opposed dies that are relatively movable toward and from eachother and by and between which a die cavity is defined; die operatingmeans for so moving the dies thereby to open and close the die cavity; acharging chamber that opens through the face of one die and is incommunication with a source of molten material at a lower elevation thansaid chamber, said source being subjected to atmospheric pressure, andimpelling means for forcing molten material from the charging chamberinto the die cavity; said improvements including in combinationtherewith a dam projecting from and fixed with respect to the other dieand arranged to enter the charging chamber upon incipient relativemovement of the dies toward each other, the dam and dies havingcontiguous parts that conjointly form a runner through which saidchamber adjacent the top thereof communicates with the die cavity, thedam being otherwise formed to fit the charging chamber to prevent theflow of molten material therefrom except through the said runner, anenclosure encompassing the dies that is adapted to be opened and closedand that is closed during relative movement of the dies toward eachother, evacuating means in communication with the enclosure for creatingtherein a vacuum of relatively high degree while the dies are apart, anda control system by which the die operating means is caused torelatively move the dies into engagement with each other and thus closethe die cavity; the impelling means is caused to act to force moltenmaterial into the die cavity to fill the latter; communication betweenthe evacuating means and the enclosure is discontinued; the material inthe die cavity as well as that in the runner and any in the chargingchamber is chilled, and the enclosure is subjected to atmosphericpressure; and the dies are moved apart and the enclosure is opened forremoval of the casting.

8. Apparatus incorporated in a die casting machine of the kind includinga first die, a second die that is movable toward and from the first die,a die cavity being defined by and between said dies, and mechanism foreffecting movement of the second die thereby to open and close the diecavity; said apparatus comprising a two-section hood that surrounds thedies, one section being adjustable in length and movable with the seconddie into engagement with the other section in advance of the meeting ofthe dies, a charging chamber that opens at its discharge end through theface of the first die, said chamber having an inlet port, a ramreciprocable in the charging chamber past said port, a darn projectingfrom the face of the second die and arranged to enter the discharge endof the charging chamber early in the movement of said second die towardthe first, the dam and dies being constituted to provide a runnerthrough which the charging chamber adjacent the top of the damcommunicates with the die cavity, the dam being otherwise formed to fitthe charging chamber to prevent the flow of molten material therefromexcept through said runner, a crucible for molten material located at alower elevation than the charging chamber and subjected to atmosphericpressure, communicative connections between the inlet port of thecharging chamber and the crucible below the minimum molten materiallevel therein, evacuating means communicating with and for creating avacuum of relatively high degree in the enclosure after the sections areengaged and before the second die engages the first die, a charge ofmolten material being induced to flow into the charging chamber underthe influence of the rarified atmosphere prevailing therein, and meansoperating to advance the ram when the dies are together for forcingmolten material from the charging chamber into the die cavity.

9. A vacuum hood for use with die casting machines of the kind includingtwo dies that are relatively movable toward and from each other, saidhood comprising two sections that surround the respective dies, onesection being composed of an inner member that is adapted to besupported in fixed relation to the corresponding die, said inner memberhaving an outwardly facing substantially continuous peripheral bearingpart, and an outer member surrounding the inner member and slidable onsaid hearing part with a substantially airtight fit, the adjacent endsof the two hood sections being disposed in abutting relation andcontacting each other with a substantially sealed joint when the diesare moved toward each other.

10. In a vacuum hood, the combination and arrangement of parts set forthin claim 9, and, in addition thereto, means for relatively adjustingsaid members in an axial direction.

11. in a vacuum hood, the combination and arrangement of parts set forthin claim 9, wherein said outer member is adjustable in an axialdirection with respect to the inner member, and means for securing theouter member in any selected position of adjustment relative to theinner member.

12. A vacuum hood for use with die casting machines of the typeincluding two dies that are relatively movable toward and from eachother, said hood being composed of two sections that surround therespective dies, one section comprising an inner member that is adaptedto be supported in fixed relation to the corresponding die, said innermember having an outwardly facing substan tially continuous peripheralbearing part, an outer member surrounding the inner member and slidableon said bearing part, means rendering substantially airtight the jointbetween said peripheral part and the surrounding part of the outermember, said outer member consisting of a top shell and a bottom shell,and means for detachably connecting said shells together, the adjacentends of the two hood sections being disposed in abutting relation whenthe die members are moved toward each other, and means for sealing thejoint between said adjacent ends of the hood sections.

13. A vacuum hood for use with die casting machines of the kindincluding two platens that are relatively movable toward and from eachother, and dies supported in opposed relation to each other by saidplatens, said hood being composed of two sections that are adapted to beattached to the respective platens and surround the dies supportedthereby, one section comprising an inner member that is adapted to beattached with a substantially leakproof joint to one of the platens,said inner member having an outwardly facing substantially continuousperipheral bearing part, an outer member made up of top and bottomshells that are detachably connected together with a leakproof joint ateach side of the outer member, the outer member surrounding the innermember and being slidable on said bearing part, means for renderingsubstantially leakproof the joint between said bearing part and thesurrounding part of the outer member, and means for adjusting the outermember axially of the inner member when the sections of the outer memberare secured together, and for retracting the top shell of the outermember when the shells are disconnected from each other, the adjacentends of the two hood sections assuming abutting relation when theplatens are relatively moved toward each other, and means rendering thejoint between said adjacent ends substantially airtight.

14. A vacuum hood for use with die casting machines of the kindincluding two dies that are relatively movable toward and from eachother, said hood being composed of two sections for surrounding therespective dies, one section comprising an inner member that is adaptedto be supported in fixed relation to the corresponding die, said innermember having an outwardly facing substantially continuous peripheralbearing part, an outer member surrounding the inner member and slidableon said bearing part with a substantially leakproof fit for adjustmentaxially of the inner member, the adjacent ends of the two hood sectionsassuming abutting relation when the dies are relatively moved towardeach other, said adjacent ends being surrounded by flanges that lie inplanes normal to the axis of the hood, a sealing gasket attached to theflange of one section for engagement with the flange of the other, and awall disposed in right angular relation to the flange to which thegasket is attached for supporting the gasket against inwarddisplacement.

15. Apparatus incorporated in a die casting machine of the kindincluding dies that are relatively movable toward and from each otherand by and between which a die cavity is defined, and operating meansfor moving the dies as aforesaid to open and close the die cavity; saidapparatus comprising an enclosure that surrounds the dies and is capableof being opened and closed and which is closed during all but theinitial and concluding parts of a cycle of operation of the machine, acharging chamber that opens at its discharge end through the face of onedie, said chamber having an inlet port, a ram reciprocable in thecharging chamber past said port and which opens the said port to theatmosphere when transferring a charge of molten material from thechamber to the die cavity, a darn projecting from the face of the otherdie and arranged to enter the discharge end of the charging chamberduring movement of the dies toward each other, the dam and dies havingopposed parts that conjointly form a runner through which the chargingchamber adjacent the top of the darn communicates with the die cavity,the dam being otherwise formed to fit the charging chamber to preventthe flow of molten material therefrom except through said runner, acrucible for molten material located at a lower elevation than thecharging chamber and subjected to atmospheric pres sure, communicativeconnections between the said inlet port and the crucible including ametering orifice restricting the flow of the molten material from thecrucible to the charging chamber during a cycle of operation of themachine to a quantity in excess of the amount needed to fill the diecavity and runner but which will not enter the runner until the ram isoperated to transfer the molten material from the charging chamber tothe die cavity, evacuating means communicating with the enclosure toevacuate the same whereby to induce the flow of the molten material fromthe crucible to the charging chamher, and means operating to advance theram when the dies are engaged to force molten material from the chargingchamber to the die cavity.

16. In a die casting machine characterized by dies that are relativelymovable toward and from each other and by and between which a die cavityis defined, a charging chamber in communication with the die cavity andarranged to permit the free flow of molten material into the die cavity,means on a die for retaining a charge of molten material in the chargingchamber while the dies are apart, a source of supply of molten materialin communication with the charging chamber, means enclosing the diecavity and adapted to be opened and closed and that is closed duringrelative movement of the dies toward each other, evacuating means forcreating in the enclosing means a vacuum of relatively high degree whilethe dies are apart and as a result of which molten material is inducedto flow from said source into the charging chamber in sufiicient amountto constitute a charge, means for metering the flow of molten materialinto the charging chamber to provide a charge of desired size while thedies are apart, means for relatively moving the dies into engagementwith each other to close the die cavity while the enclosure is inevacuated condition, and means for displacing the charge of moltenmaterial from the charging chamber into the die cavity.

17. In a die casting machine characterized by dies that are relativelymovable toward and from each other and by and between which a die cavityis defined, a charging chamber in communication with the die cavity andarranged to permit the free flow of molten material into the die cavity,means on a die for retaining a charge of molten material in the chargingchamber while the dies are apart, a source of supply of molten materialat a lower elevation than said charging chamber and that is incommunication therewith, an enclosure surrounding the die cavity andadapted to be opened and closed and that is closed during relativemovement of the dies toward each other, evacuating means for creating inthe en'- closure a vacuum of relatively high degree while the dies areapart and as a result of which molten material is induced to flow fromsaid source into the charging chamber, means for metering the flow ofmolten material into the charging chamber to provide a charge of desiredsize while the dies are apart, means for relatively mov ing the diesinto engagement with each other to close the die cavity while theenclosure is in evacuated condition, and means for displacing the chargeof molten ma terial from the charging chamber into the die cavity.

18. In the method of die casting wherein molten material is deliveredinitially from a container to an interconnected charging chamber and issubsequently delivered to an interconnected die cavity defined by andbetween two relatively movable die members, the improvement comprisingin combination therewith the steps of subjecting the interior of the diecavity to a high degree of vacuum and thereby also subjecting thecharging chamber to vacuum to induce flow of the molten ma terial fromthe container to the charging chamber, simultaneously metering the flowof molten material so as to provide a charge of desired size in thecharging chamber while at the same time partially closing communicationbetween the charging chamber and the die cavity so as to retain themolten material in said chamber while the die members are still apartbut are moving toward each other, engaging the die members to close thedie cavity, forcing the flow of the molten material from the chargingchamber into the die cavity, thereafter chilling the molten material inthe die cavity to solidify it and to form a casting, and moving the diemembers apart for the removal of the formed casting.

19. In the method of die casting wherein molten material is deliveredinitially from a container to an interconnected charging chamber and issubsequently delivered to an interconnected die cavity defined by andbetween two relatively movable die members, the improve ment comprisingin combination therewith the steps of surrounding the die cavity with asubstantially air-tight enclosure, subjecting the interior of theenclosure to a high degree of vacuum while the die members are sepaparated and thereby also subjecting the die cavity and the chargingchamber to vacuum to induce flow of the molten material from thecontainer to the charging chamber, at the same time metering the flow ofthe molten material from the container to the charging chamber so as toprovide a predetermined charge while partially closing communicationbetween the charging chamber and the die cavity so as to retain themolten material in the charging chamber while the die members are stillapart but are moving toward each other, moving the die members to closethe die cavity while the vac uum prevails, forcing the flow of themolten material from the charging chamber into the die cavity,thereafter chilling the molten material in the die cavity to solidify itand to form a casting, and opening the enclosure and moving the diemembers apart for the removal of the formed casting.

References Cited in the file of this patent UNITED STATES PATENTS Re.18,202 Polak Sept. 22, 1931 2,243,835 Brunner June 3, 1941 2,544,598Kalina Mar. 6, 1951 2,799,066 Federman July 16, 1957 FOREIGN PATENTS1,004,268 France Nov. 28, 1951

